The major objective of this proposal is to investigate the role that cytotoxic lymphocytes play in the pathogenesis of Herpes simplex virus type 1 (HSV-1) corneal lesions and to use this information in an attempt to intervene in the infectious process through manipulation of the cytotoxic response. Our preliminary observations suggest that such intervention may be feasible. The studies contained in this proposal will achieve three major goals. First, the cytotoxic activity that develps in the PBL following topical corneal (TC), intracameral (IC), and footpad (FP) infection with HSV-1 will be further characterized with regard to: (l) the involvement of interferon (IFN) in the early activation of non-specific cytoxic activity in PBL, (2) the infection, and (3) the capacity of in vitro HSV-1 stimulation to augment the cytotoxic activity of PBL. These studies will utilize a standard IFN assay to quantitate IFN in serum and culture supernatants, and a standard chromium release assay to measure cytotoxic activity against HSV-1 infected class I MHC compatible and incompatible targets and YAC-1 (NK-sensitive) targets. The cytotoxic activity that develops in RLN cells following IC, TC, and FP HSV-1 infection will be further characterized. The involvement of IFN, IL-2, and other soluble factors in the HSV-1 stimulated augmentation of cytotoxic activity will be tested. The mechanism by which the cytotoxic activity of RLN cells from IC infected mice is suppressed will also be investigated. These studies will involve in vitro lymphocyte subpopulation depletion, mixing experiments, and assays for the detection of soluble suppressor factors in culture supernatants of HSV-1 stimulated RLN(IC) cells, as well as in vivo experiments involving splenectomy and adoptive transfer. The information gained in the first two section of the proposed studies will then be used in an attempt to intervene in the HSV-1 infectious process through manipulation of the cytotoxic response. The studies in this section will: (l1) determine the involvement of IC infection-induced suppressor cells in the protection against corneal lesions afforded to TC-infected mice by simultaneous IC infection, (2) determine the involvement of cytotoxic lymphocytes in the pathogenesis of herpetic corneal lesions, and (3) determine the role of PBL NK cells in protection against corneal lesions.